Photoelastic and holographic analysis of a turbine-engine component

Isopachics obtained by holographic methods are combined with the isochromatics and isoclinics of a conventional photoelastic analysis to obtain a complete two-dimensional stress analysis of a highly critical region of a jet engine. The analysis of the disk/blade dovetail region of the third stage fan of a turbine engine shows a stress-concentration factor of 5.2 in the disk fillet and 4.8 in the blade fillet relative to the average stress in the neck section of the disk. The stress distribution along the edge of the blade fillet and on an interior line in the disk lug is also reported. Preliminary redesign of the disk fillet indicates that a 27-percent reduction in the fillet stress of existing third-stage disks is possible by remachining the relief area between the blade and disk lugs.